1. Field of the Invention
The invention relates to a device for supplying a purified gas to a plant which is purged using this purified gas, comprising a feed line which is connected, on the one hand, to a source of the purified gas and, on the other hand, to an inlet of the plant.
2. Description of the Related Art
A wide variety of plants, for example in the fabrication of electronic components, require the use of filtered and inert atmospheres.
For example, silicon wafers intended to carry microelectronics circuits are stored in an enclosed space with a nitrogen atmosphere which has only a few ppm of impurities, consisting in particular of oxygen. One example for storing and transporting wafers is described in U.S. Pat. No. 5,644,855.
Given that the purified gas is progressively contaminated with impurities, it is necessary to replenish the nitrogen atmosphere in the enclosed space as time progresses. This replenishment is generally carried out by supplying the enclosed space constantly with a certain flow of purified nitrogen coming from a purified gas source, and by discharging the contaminated nitrogen.
However, the cost of purified nitrogen is very high, so that replenishing the inert atmosphere in the storage space represents a significant contribution to its running costs.
Furthermore, these known plants also have the drawback that, if there is a fault with the source of the purified gas, all parts of the plant which are purged will be affected by this, which in the aforementioned example may make it necessary to discard all the silicon wafers stored.
Systems for separating gases using a membrane, which are applicable to electronics or other fields, are known in particular from EP-A-754 487 as well as U.S. Pat. Nos. 5,308,382, 5,240,471, 5,290,341, 5,378,439 and 5,383,957.
The object of the invention is to overcome these various drawbacks by providing a device for supplying a purified gas, in particular nitrogen, to a plant such as, for example, a wafer storage space for microelectronics, which makes it possible on the one hand to reduce the running cost of such a plant and, on the other hand, to give the plant some degree of autonomy from the source.